The present invention relates to a technology for suppressing degradation of image quality in the case where data lines are driven in a block for a plurality lines.
In recent years, projectors using electro-optical panels, such as liquid crystal panels, to form small images and for amplifying and projecting the small images on a screen or a wall with an optical system have been widely used. These projectors do not have a function to form images on their own, but receive image data (or image signals) from some higher-level devices, such as PCs or television tuners. The image data designates a gray-scale level (brightness) of a pixel, and is supplied in a vertical-scanning-type manner or a horizontal-scanning-type method to pixels arranged in a matrix, so that it is desirable even for an electro-optical panel for use in a projector to be driven in these ways. Therefore, an electro-optical panel for use in a projector selects scanning lines one after another, and sequentially selects data lines one-by-one for a period where one scanning line is selected (one horizontal scanning period), and the image data is generally driven using a point sequential method, such that the image data, transformed to be suitable for driving the liquid crystal, is supplied to the selected data line.
However, recently, there has been a strong demand for high precision in response to developments in high-definition technology. High definition can be achieved by increasing the number of scanning lines and the number of data lines, and one horizontal scanning period becomes reduced due to the increase in the number of scanning lines. Furthermore, with the point sequential method, the period for selecting data lines is also reduced due to the increase in the number of data lines. For this reason, with the point sequential method, an insufficient time can be obtained to supply image signals to the data lines, as high-definition technology progresses, causing the pixels to be insufficiently written.
With the aim of overcoming the insufficient writing described above, phase expansion driving has been proposed. The phase expansion method refers to a method in which a predetermined number of the data lines (e.g., 6 data lines) are selected for every one horizontal scanning period, and image signals of the pixels corresponding to intersections of the selected scanning lines and the selected data lines are selected and extended by 6 times along the time axis to supply them to each of the 6 data lines. It has been understood that phase expansion driving is suitable for high definition since the time for supplying image signals to the data lines can be extended 6 times longer than that for the point sequential method.
However, in the phase expansion drive, a plurality of data lines are selected at the same time, resulting in degradation of image quality.